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Math Help - Graph w/ 2 points of intersection

  1. #1
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    Exclamation Graph w/ 2 points of intersection

    Graph the 2 lines below; and from your graph, read off the point of intersection.

    y = 2x + 3

    y = x + 5

    I'm at the utmost of confusion here. I have began to work this problem out and have come up with a bit of a road block here. It looks like I hit a brick wall literally. If anyone can help I would greatly appreciate it.

    Thanks so much in advance

    Brinalynn
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  2. #2
    A riddle wrapped in an enigma
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    Quote Originally Posted by Brinalynn View Post
    Graph the 2 lines below; and from your graph, read off the point of intersection.

    y = 2x + 3

    y = x + 5

    I'm at the utmost of confusion here. I have began to work this problem out and have come up with a bit of a road block here. It looks like I hit a brick wall literally. If anyone can help I would greatly appreciate it.

    Thanks so much in advance

    Brinalynn
    Hi Brinalynn,

    You need to set up a couple of tables like this:

    Code:
    y = 2x + 3     y = x + 5
     
    x | y             x | y 
    -----            -----
    0 | 3             0 | 5
    1 |               1 |
    -1|              -1 |
     2|                2|
    -2|               -2|
    Assign arbitrary values for x, and then solve for y. Start out using small integer values of x, both positive and negative. Start with x = 0 to obtain your y intercepts for both lines. Use as many values for x as necessary until you find the same ordered pair in each table. This would be your point of intersection.

    Plot these points on your graph and try to determine the point of intersection visually. The more careful you are when plotting and using a straightedge to draw your lines, the better your chances of finding the correct point of intersection.

    Test the point of intersection into both equations to make sure it is the correct point.

    Give it a shot.
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  3. #3
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    You could graph the equations but I'll show you the substitution method just in case...

    Basically we have 2 equations. In this case

    y = 2x + 3

    y = x + 5

    alright?

    you see if y is equal to 2x+3 and x + 5 in the second one. So we can substitute one of the equation's y and replace it to what the other y equals to.

    So we have:

    x + 5 = 2x + 3

    then solve for x...

    -1x = -2

    x = 2

    now substitute x back in into one of the equations to get y.
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